Fire detecting and alarm mechanism



Feb. 8, 1938. J. H. DERBY 2,107,525

FIRE DETECTING AND ALARM MECHANISM Filed Jan. 8, 1935 2 Sheets-Sheet l n I Thermosfial Zc Circuii Closer MWWW ATTORNEYS.

Feb. 8, 1938. J, H. DERBY FIRE DETECTING AND ALARM MECHANISM 2 Sheets-Sheet 2 Filed Jan. 8, 1935 IIIIIIII' INVENTOR. Ja /v 6. Awa

ATTORNEYS.

Patented Feb. 8, 1938 UNITED STATES PATENT OFFICE This invention relates to fire alarm systems, and particularly to a combined fire detector and alarm unit adapted for convenient installation in and operation from alternating current house and building lighting systems.

Although approved thermally-operated fire de' 1 tecting units, such as metallic couples, fusible alloy bridges, switch actuators acting upon a predetermined rate of rise of temperature and explosive element switch releases, for closing alarm circuits, have long been on the market, difliculty has been encountered in getting them into general use, particularly in private homes, because of the fact that they require considerable wiring to effect their installation, thus usually requiring the services of an expert electrician and also of a person sufliciently familiar with the action of fires to know where the detecting units sli ould be located. Because of the expense and trouble connected with their installation and of the necessity for instructing those who install them in the manner of installation, the sales and service organizations required to market such fire prevention systems have seemed so large and costly in proportion to the probable market that makers of such apparatus have not been able to interest capital in the house and small building field and thus the very desirable, more extended use of fire-detecting and signallingsystems in homes and minor public and semi-public buildirlijgs such as schools and stores has not yet come a cut.

One of the aims of the present invention is to provide'an improved, compact and relatively inexpensive unit of the type which includes both fire-detecting and alarm giving mechanism and which does not require the use of specially skilled men for its installation, whereby homes and small may readily be protection, at least of danger.

The invention aims further to provide a unit of this kind that is substantially fool-proof and that is so constructed that it will not be affected by dust, dampness or the corrosive influences usually present in locations where fires are apt to start. At the same time the invention aims to provide such simple and easy means for testing the operativeness of the unit that anyone can tell at any time whether or not it is in operative condition.

An important feature of the invention is the provision of a combined, readily installed unit, containing both detecting and alarm mechanisms, which is so constructed that it canreadily be connected to additional detecting units whereby one can easily add to the protected area covered by the fire prevention system.

An important object of the invention is to provide a device for the purposes set forth which.

given fire prevention at the more obvious points nected to an electric while it is so constructed that it is sure to function when the occasion arises, is not liable to give false alarms and which, when it has operated, can quickly and easily be restored to operative condition by the owner thereof and without the use of skilled labor.

Among the important features of the invention are thenovel construction and arrangement or the sound-producing diaphragm, the provision of vents in the housing on both sides of the diaphragm so that sound waves may be propagated from both faces thereof and so that there will be no interference with the vibrating movements oi said diaphgrarn, and the provision for conveniently connecting anextension signal to the detecting means.

Other important features and objects of the invention will appear when the following description and claim are considered in connection with the accompanying drawings, in which Figure 1 is a vertical section through a combined fire detecting and alarm unit embodying the present invention;

Figure 2 1s another vertical section through said unit at right angles to the section shown in Figure 1;-

Figure 3 is a wiring diagram;

Figure 4 is a section on the line 4-4' Figure 1;

Figure 5 is a section on the line 5-5 of Figure-1;

Figure 6 is a bottom plan view, and

Figure 7 is a perspective of the thermostatic circuit closer unit.

In the illustrative embodiment of the invention the housing 2 in which the elements of the combined fire detecting and alarm unit are enclosed and by which they are supported is consocket plug, preferably of the screw type to insure permanent connection, said plug having the usual core of insulation 5, the usual sheet metal conductor t, provided with the socket threads, and the usual central conductor B in the form oi a bolt preferably long enough toserve to clamp the housing 2 to the socket plug. a

As herein shown, the housing 2 of any suitable material, preferably a not readily corrodible metal, is provided with a central opening at its top through which an insulating bushing iii passes. The bolt 8, which extends through the bushing It, is provided at its lower end with a nut i2 and a washer it which clamps against an insu-' lating washer is on the inner side of the housing 2. Between the base of the plug and the outer face of the housing is a second insulating washer i3 which preferably forms one of a pair of clamp members between which and the other insulating clamp washer to a metal canopy 22 is clamped, the purpose of this canopy 22 being to shield the vent openings 24 in the top of the housing 2 from dust particles dropping through the air or from the ceiling on which the unit is mounted.

The sheet metal conductor 6- extends beneath the insulating core 4 where it is engaged by an extension piece in the form of a rivet 28 passing through a second opening in the housing 2 and through corresponding openings-in the washers I8, I8 and 28 into the interior of the housing 2 where it may be connected to the wiring circuit of the unit. A bushing 28 insulates the extension member 24 from the housing 2.

As shown in Figure 2, the wall of the housing 2 is thickened at diametrically opposite sides to provide for proper support for a push button switch 38 and for a 3-way socket 32 for connecting additional thermostatic circuit closers to the normally open alarm circuit, and for connecting an extension alarm. The functions of these parts will be set forth more fully hereinbelow. This thickening of the housing alsolprovides shoulders or abutments 34 and 38 against which are clamped two rings of non-magnetic 'material 38- and 48, the ring 38 being provided with a rabbet 42 on its edge adjacent to the ring 48 whereby a groove is provided between the two rings to receive the edge of a non-metallic sound diaphragm '44 which may be made of any material suitable for the purposes. In practice it has been found that a diaphragm made of a paper base impregnated with bakelite or other phenol-formaldehyde condensation product has the desired sound producing properties. The rabbet 42 is preferably of sumcient depth to allow the diaphragm to move bodily in a direction perpendicular to its plane, this bodily movement apparently increasing the sound effect.

The rings 38 and 48 are clamped to the shoulders or abutments-34 and 36 by screws 48 which also preferably serve to clamp a crossbar -48 of insulating material to the housing, spacing washers 58 being preferably provided between the lower ring 48 and the crossbar 48.

The upper ring 38 also serves as a support for the alternating current magnet structure now to be described. This magnet, which has its axle extending across the housing at right angles to the insulating bar 48, comprises a coil 52 and a core 54 provided with the usual slot 56 employed in alternating current magnet cores. Connected to the two ends of the core 54 by screws 51 are polar extensions 58 and 68 in the formof angle pieces having their polar ends 82 and 64 suitably spaced above an armature 68 carried by and connected to the non-metallic diaphragm 44. The armature 66 is preferably in the form of a piece of soft iron or steel located on the upper side of the diaphragm 44. A piece of aluminum 61 on the opposite face of the diaphragm riveted to the armature provides suitable connection. It will be noted that the armature bridges the gap between the two poles 82 and 84 and is spaced from the poles a sufficient distance to allow for free vibration of the diaphragm while at the same time being in attractive relation to the poles.

The magnet is secured in position in the casing by screws 68 and 18 which extend through the rings 38 and 48 and into the pole extensions 58 and 68 near the corners of these extensions, the

screws 88 and 18 also serving to clamp against the under face of the ring 48 brackets I2 and 14 to which the combined housing end closer and thermostatic circuit closer carrier may be se cured by means of screws I8.

In order to provide for convenient restoration of the combined fire detecting and alarm unit to operative condition when the thermostatic circuit-closing element has operated to close the alarm circuit, the illustrative construction has been so designed that a standard outlet unit, such as has been designed for use with ordinary outlet boxes, can be connected to the open lower end of the housing by the screws 16 threaded into the brackets I2 and I4 and that, when so connected,

shouldered projections 88 for so spacing the thermostatic circuit closer 82 from the base that air may reach both faces of it. The said circuit closer is preferably of the type described and claimed in my application for United States Letters Patent Serial No. 619,181, filed June 25, 1932, and comprises in general two spaced metallic disks and a fusible element which, at a predetermined temperature, will fuse and unite the two disks to close a circuit of which they are the terminals, one of said disks being provided with a terminal extension 84 and the other with a terminal extension 86 connected respectively by flat headed screws 88 and 98 to the base I8. The flat heads of these screws 88 and 98 serve as contacts to engage spring-ejected plungers 92 and 94 guided in cylinders 98 and 98 screwed upon bases I88 and I82 connected by bolts I84 to the insulating crossbar 48, suitable electric connectionsbeing made to the bases I88 and I82 through the bolts I84. Springs I88 in the cylinders 88 and 98 serve to eject the plungers 82 and 94 and thus hold the plungers 92 and 94 in intimate electrical contact with. the flat heads of the screws 88 and 98.

The separating rib I88 on the base 18, which is a part of the standard outlet unit used in the present construction, serves no useful purpose in this construction since there is no liability to short-circuiting across from one of the terminals 84 and 88 to the other by reason of projecting or loose wires.

4 To insure free vibration of the diaphragm 44 and propagation of sound waves from both faces thereof, the lower part of the housing 2 is provided with vent openings 8 which serve the same purpose as the vent openings 24 in the upper chamber of the housing, the diaphragm 44 dividing the housing into two chambers.

The electrical connections between the different elements of the structure hereinabove. described are shown in the wiring diagram in Figure 3. It will be understood that the unit is designed to be connected to an ordinary screw socket of an alternating current house or other building lighting system and that when so connected the conductor 8 of the plug is connected to one side of the wiring circuit and the bolt or conductor .8 of the plug is connected to the other side of the circuit. One side of the circuit includes the rivet extension 28 of the conductor 8, wire II2-and the terminal 84. The other side of the circuit includes the bolt 8 of the plug, wire I I4, coil 52 of the magnet, wire 6 and the other terminal .88. When, therefore, the terminals 84 and 88 are connected by the fusion at a predek proper connection being made.

' circuit closer extension circuit is connected.

aromas termined temperature of the fusible element of the thermostatic circuit closer 82, a circuit is closed through the coil 52 of the alternating current magnet which results in the armature fit being alternately attracted and repelled. by the poles 02 and 6d, thus setting up a rapid vibration of the diaphragm and producing a loud and com paratively high-pitched sound.

In order to test the apparatus, the push button switch til is connected to the two sides of the circuit in parallel with the terminals 86 and 853, and between said terminals and the coil 52 whereby the push button may short-circuit the thermostatic circuit closer and thus effect the manual closing of a circuit through the coil 52 to test the alarm mechanism.

An important feature of the invention is the provision for connection to the alarm mechanism of other thermostatic circuit closers besides the one which constitutes a part of the combined unit. This permits the operation of the alarm by thermostatic circuit closers located'at other points where fires may start. Provision is preferably also made for connecting to the combined unit another alarm mechanism, which may be located at some other point in the building, so that when the occupants of the building are remote from the point where the combined unit is located they will still have an alarm within easy hearing distance.

In the illustrative embodiment of the invention very simple means have been provided for making these extension connections, both for the additional thermostatic circuit closers and for the extension alarm, in the provision of the 3- way receptacle t2 herelnabove referred to. This 3-way receptacle is adapted to receive a plug I20 having thereon three pins 522, I26 and I26 adapted to be received in correspondingly located sockets in the receptacle t2, one of the pins I26 being of larger diameter than the other two to lnsur The plug I20 is preferably permanently connected by a suitable cable to a transformer box I28, shown in Figure 3 merely diagrammatically, which will be furnished with the unit when extensions are desired in order to insure that the user will make the proper connections.

Referring to Figure 3, which illustrates the wiring diagram and particularly the connections through the receptacle 32 and plug I20 to the transformer box I28 from which the extension connections can readily be made without expert service, it will be seen that one of the pins of the plug I20 is connected by a wire I30 to one side of the primary coil I32 01 the transformer and that another pin of the plug I20 is connected by wire I32 to the other side of the primary coil I32 and also to a branch wire I 34 that goes to a binding post I36 on the transformer box I28 for connection to one side I 31 of the thermostatic circuit closer extension circuit. Thethlrd pin of the plug I20 is connected by wire I38 to the other binding post I40 to which the other side I of the thermostatic The secondary coil I42 of the transformer is connected to two binding posts I and. I46 on the transformer box to which the two sides of the extension circuit for the extension alarm I48 are connected. This alarm may be of the same type as the alarm comprised in the combined unit, but preferably operating at the lower voltage provided by the transformer.

The corresponding three sockets in the receptacle 32 for the pins of the plug I 20, to which reference has just been made, are connected to the circuits inside the unit as follows:

The socket which receives the pin connected to the wire I30 is connected by a wire I50 to the wire ill at a point between the coil 52 and the bolt 0. The socket for the pin which is connectedto the wire liitand also to thebranch wire we is connected by a wire N52 to the wire H5 at a point on said wire between the coil 52 and the terminal 06 of the thermostatic circuit closer. It will thus be seen that the primary coil E32 of the transformer is connected to one side of the circuit in parallel or multiple or in shunt with the coil 52 of the alternating current magnet, the connection being on that side of the open circuit which includes the wire Hi. Therefore no signal will be given either in the combined unit itself or by the extension signal I48 until the circuit, which includes the wires H2 and IN is closed either by the thermostatic circult closer 82 in the unit itself or by one of the extension circuit closers M3 arranged in parallel therewith, as hereinafter set forth.

The third socket, which receives the pin connected to the wire lid, is itself connected by a wire I54 to the wire IE2 at a point between the terminal 84 of the thermostatic circuit closer in the unit itself and the rivet 26. From this it will be seen that the two sides I 31 and MI of the extension circuit for the extension thermostatic circuit closers I43 are connected in parallel with the circuit terminals 0 and B6 and. between said terminals and the bolt 0 and rivet 26 whereby able labels or other indicia on the binding posts I36, I40, I44 and I40 to show the manner of connection of the extension, circuits, so as to prevent as far as possible improper connection of these circuits.

What I claim as new is:

A combined fire detector and alarm unit comprising, in combination, an electric socket connection by which said unit may be both supported irom an electric socket and connected with a.

source of supply of alternating current, a housing carried by said socket connection, a sound diaphragm dividing said housing into two compartments, an alternating current magnet in one compartment, a magnet armature carried by said diaphragm in attractive relation to said magnet, a thermostatic circuit closer forming also a closure for said housing, a normally open circuit including said socket connection, said magnet, and said thermostatic circuit closer, each of said compartments in said housing being vented to the atmosphere to permit sound waves to be propagated from both faces of said diaphragm.

' JOHN H. DERBY. 

